1. Field of the Invention
The present invention generally relates to computer apparatus and, in a preferred embodiment thereof, more particularly relates to the hot pluggable, redundant connection of adapter cards, such as hard disk drive array controller cards, to an associated I/O board in a computer system such as a server system.
2. Description of Related Art
In a conventionally constructed computer server system a series of portable media storage devices, typically hard disk drives, are removably insertable into support cage structures and are provided with electrical connectors that are removably mateable with corresponding connectors on back plane circuit boards within the support cage structures in response to insertion of the disk drives into their associated cage structures.
This conventional type of server system also typically comprises a system I/O board having one or more array controller cards thereon which are used to control the operation of the cage-supported hard disk drives. The array controller cards are electrically coupled to the back plane connectors within the support cage structures by means of flexible cables suitably interconnected between the back plane circuit boards and cable connectors mounted on the array controller cards.
For a variety of reasons it has become desirable to provide computer server systems of this type with array controller card hot plug redundancy such that (1) each controller card has a backup-card on the I/O board which can assume control of the associated disk drive(s) if the first card fails, and (2) during system operation any array controller card or its back-up card may be removed from the I/O board without disrupting hard disk drive operation or server system operation.
Attempts to provide this desirable controller card hot plug redundancy have, however, been frustrated by current cabling configurations of available array controller cards. Specifically, conventional array controller cards have one or more cable connectors provided thereon to which one or more electrical ribbon or bundled cable ends may be coupled. When a conventionally constructed controller card and an associated redundant back-up controller card are to be operatively connected to a support cage back plane circuit board, it is necessary to utilize a ribbon cable with three mating connectors. The connectors are located at each end of the cable, and some suitable distance along the length of the cable. One end of the cable is connected to the first card. The connector along the length of the cable is connected to the second card, and the other end of the cable is connected to the back plane circuit board.
Such required card interconnection cabling technique can provide the server system with controller card redundancy, but undesirably breaks the connection between the two cards and their associated back plane circuit board in the event that the second controller card (i.e., the one to which the connector along the length of the ribbon cable is connected) has to be removed from the I/O board. This is due to the fact that the second card is, in effect, "trapped" by the external cabling, which has to be disconnected from both cards to allow the second card to be removed from the I/O board. In turn, this undesirably terminates electrical communication between both cards and the back plane circuit board, and prevents the desired hot plug connection of the second card to the system I/O board.
This hot plug redundancy connection problem, to which the present invention is directed, is not limited to array controller cards in computer server systems, but is also manifested in systems utilizing other types of adapter cards such as, for example, network interface adapter cards and system management cards.